Process for the treatment of alkylolamine soaps and related products



Patented July 9, 1935 UNITED STATES PROCESS FOR- THE TREATMENT OFALKYLOLAMINE SOAPS AND RELATED Walter J. Hand and Ludwig Francisco,Calif.

Rosenstein, San

7 No Drawing. Application April 11, 1933,

Serial No. 665,556 r 18 Claims.

The invention appertains broadly to the recovery of alkylolainines fromtheir soaps with fatty acids and more particularly is concerned with therecovery of alkylolamines from the extracts obtained in the refining ofliquefied or normally liquid masses (containing fatty acids, naphthenicacids, etc.) with alkylolamine, said extracts being described in ourPatent No. 1,885,- 859 issued November 1, 1932 as being derivable fromanimal oils, vegetable oils, fats, waxes, resins and the like.

As the refining of fatty oils andfsimilar masses, as described above,with alkylolamine is carried out with an excess of alkylolamine over thestoi chiometric requirements of the free fatty' acid present in saidoleagincus material, such excess serving as a solvent for thealkylolamine salts (soaps) of the fatty acids and other extracts (suchas coloring matter, ketones and other components soluble in alkylolamineand desirable to remove by extraction therewith) and, asameans ofattaining the proper volume relationships between the glyceride andalkylolamine phases necessary for efficiently effecting their separationby centrifuging, settling or equivalent physical modes; the condition ofthe alkylolamine in the extract is as both free and combinedalkylolamine.

The free alkylolamine can be removed from the extracts, in question, bydistillation, although it is preferable to conduct the operation atreduced pressures, whereby an avoidance of superheating is obtained. Ofcourse, this separation holds'true only when the boiling temperature ofthe alkylolamine is below that of the fatty acid (which has beenextracted in the combined form as a soap or salt) Superheating, orelevating the temperature of the extract to the boiling temperature ofthe alkylolamine at atmospheric pressure enhances certain chemicalchanges in the extract which it may be desirable to avoid. These areamidizaticn of the fatty acid of any glycerides (which are soluble to aslight extent in the extract) and liberation of their glycerol, andmodification or decomposition of other sensitive substances, such asketones and aldehydeawhich may be contained in the extract. It ispreferable also to conduct this distillation for free alkylolaminerecovery at reduced (subatmospheric) pressures in the presence of steam,as an aid to the removal of alkylolamine vapor from the distillationsystem, to facilitate its removal at lower temperatures, and to suppressamidization of the.

fatty acid of glycerides or amidization of the alkylolamine-combinedfatty acid. Thus, by suitably reducing-the pressure, it is possible torecover the free alkylolamine, for example, monoethanolamine,entirelyfrom the extracts at temperatures as low as 60 C.

As the extract becomes concentrated with.respect to combinedalkylolamine, it assumes the with combined ethanolamine at gelatinousconsistency of alkylolamine soap, and this state interferes with theconductance of the distillation. By maintaining the vacuum and elevatingthe temperature in the still boiler above the melting temperature of thesoap gel at the existing pressure, or by lowering the reduced pressureandraising the temperature, these soap gels again become, fluid and thedistillation may be carried on further with steam. A substantiallycomplete recovery of the free alkylolamine may be obtained.

the distillation apparatus may be so designed as to provide for afractional condensation of alkylolamine and Water and a separation ofthe alkylolamine from the distillation vapors substantially asalkylolarnine with a low Water content.

We have found that the combined alkylolamine may be recovered from itssalts with the fatty acids by the steam hydrolysis of the same. Whilethis combined alkylolamine may be recovered by chemical means, such asliberation from the salt by adding alkali and distilling, as in the caseof free alkylolamine recovery, or by acidifying with a suitable acid assulfuric acid to liberate the fatty acid, skimming oif the liberatedfatty acid, liberating the alkylolamine by interaction of thealkylolamine sulfate with a suitable base such as the alkaline earthoxides, hydroxides, carbonates,

etc. to form an insoluble inorganic salt, as, for

example, calcium sulfate and an aqueous solution of thefreedalkylolamine which may then be concentrated; it is preferable to recoverit by the physical means of steam distillation,

In conducting the distillationor hydrolysis with steam of alkylolaminesoaps for the recovery of the combined alkylolamine, the charge isbrought to a temperature necessary for liquefying the soap gel. Thetemperature selected is dependent upon the vacuum applied. For instance,working 100 mm. Hg. pressure, a suitable temperature is 140 C. while atpressures below 20 mm. Hg. recovery of ethanolamine is eliective at 120'C.

The rate 'of the hydrolysis with steam of allrylolamine salts of fattyacids is dependent upon raising the temperature of the material beinghydrolyzed to a suiiicient degree above the boiling temperature of freealkylolamine at the pressure- Within the system and providing goodcontact with an amount of steam preferably in excess of the absolute"requirements for the hydro1ysis..- Thisprocedure is to be adopted forthe 2 relatively low-boiling alkylolamines such as monoethanolamine,monopropanolamine, monoisobutanolamine, and the like and fatty acidswhich are the usual run of acids to be found in most natural fattyoleaginous compositions, that is, such fatty acids having boilingtemperatures approaching or exceeding 200 C. at 15 mm. Hg. pressure.Where the boiling temperature of the fatty acid is below that of thealkylolamine used, it will be seen that the fatty acid will distill overfirst or together with the alkylolamine.

In the case of distillation with an insufficient amount of steam, wehave found that an alteration of alkylclamine soap takes place whichcorresponds to the amidization of a fatty acid by the dehydration of itsammonium salt. In the case of ethanolamine oleate. oleic acid amidol isformed, which has the formula.

C17H33.CONH.C2H4.0H.

The formation of acid amidols from alkylolamine salts of fatty acidsduring the course of a steam distillation with limited amounts of steamfor the recovery of combined alkylolamine is evidenced by a rapid dropin the rate of alkylolamine recovery, low alkylolamine recoveries and bya residuum which is not clear but opaque and which, on cooling andstanding, deposits white crystals easil distinguishable from normal freefatty acid crystals which might separate out from mixed fatty acids. Thefatty acid amidols have a low solubilit in organic solvents as gasoline,petroleum benzine, etc. and may be washed free of fatty acid andalkylolamine soap therewith. They are readily soluble in alcohol andfairly soluble in ether from which they may be recrystallized. The acidamidol from oleic acid and ethanolamine has a melting point of 9l92 C.and is a white, fluffy micro-crystalline mass. This acid amidol as wellas those of other fatty acids, particularly of unsaturated fatty acids,such as those in sardine oil, have characteristics which make them ofvalue as emulsifying agents and paper sizes.

The amidization of alkylolamine salts of fatty acids may be suppressedby providing intimate contact of excess steam with material to behydrolyzed. As there are cetrain difficulties in the way of providingfor such perfect contact, which are: lack of means of suitabledistribution of steam within the mass so as to prevent localsuperheating in the absence of sufficient water vapor, difficulty incontrolling the excessive foaming which results when such intimatecontact is provided, excessive dilution of the alkylolamine in thedistillates with water, and excessive steam consumption,another means ofsuppressing amidization was found.

We have discovered that the addition of alkali, such as the oxides,hydroxides, carbonates, etc. of sodium, potassium and the like, oralkali salts of fatty acids such as the sodium or potassium salts ofoleic, palmitic, stearic acids, etc. in comparatively small amounts,very much less than the stoichiometrical requirements, acted strongly tosuppress amide formation and consequently enhanced the alkylolaminerecoveries from the steam hydrolysis of alkylolamine-fatty acid mixturesat reduced pressures, elevated temperatures and limited. amounts ofsteam. Those alkalis are selected which will react with the fatty acidto form its soap and yet be sufficiently dispersed therein to effectsuppression of amidization.

The following tables show the effect of variables on the recoveries ofethanolamine from ethanolamine-fatty acid mixtures (from neutral soapsto excess of fatty acid) by steam hydrolysis.

TABLE I Eflect of concentration of ethanolamine and temperature on thedecomposition of ehtanolamine-sardine oil fatty acids at 100 mm. Hg. andwith a fixed steam rate, as dete mined by the ratio of water:ethanolamine in the distillates gg g gfi Tempera- Weight ethanolammeture of deratio H2O: PM m 01 composiethanol- Iatty acid tlon amine TABLEII E fleet of varying steam rate, composition of charge and KOH on thetotal recovery 0/ ethanolamine from ethanolamine combined with fattyacid by steam distillation at 140 and 100 mm. Hg.

TABLE III Efiect of KOH concentrat on on ethanolamine recovery by steamdistillation at 120 and 14- 35 mm. Hg. pressure Stearn rat/c Ethanolgm.min. amine Composition of charge mols per mol kilo 0 recovery charge ofcharge It has been shown that amounts of alkali less than 0.2 mol permol of fatty acids are very effective in the recovery of freealkylolamine. Larger amounts may be used to accomplish the 2,007,166same result. However, excesses'are to be avoided as they necessitateother steps such as an acid treatment to recover the fatty acid (fromthe residues after alkylolamine removal).

The free fatty acid, remaining after alkylolamine removal, may berecovered from the distillation residues by steam distillation at anelevated temperature and at reducedpressures.

The data given in Tables I, II and III are designed to indicate,respectively, theminimum water requirements for the hydrolysis ofalkylolamine soaps, the effect of small increases of water (over theseminimum requirements) on alkylolamine recovery and the effect of alkaliconcentration on alkylolamine recovery. It has been found thatalkylolamine recovery is dependent, under conditions where thehydrolysis of the soaps become possible, upon the suppression ofamidization of the fatty acid. The data in Tables II and III demonstratethe effect of small increases of steam and small amount of alkali insuppressing amidization and effecting,

therefore, increased ethanolamine recovery. With large amounts of steam,at substantially complete recovery of ethanolamine may be-obtained. Forexample, in a distillation ofneutral ethanolamine soap of cottonseedfatty acids with steam at approximately 60 gm. per min. per kilo ofcharge, with a starting temperature of 55 C. and an end. temperature ofat a pressure equal to the vapor pressure of water at 15C., andcontinuation of the distillation until fatty acids congeal in thecondenser, a 97.2% recovery of the ethanolamine was obtained.

It should be noted that the examples given represent the extremesbetween minimum steam requirements for the hydrolysis and a-large excessof steam, using laboratory equipment. As is well-known, distillations ofthis type may be effected with much greater efficiencies in commercialequipment, for many devices operating to obtain improved contact betweenmaterial and steam then may be used which could not be adapted to smalllaboratory equipment. Therefore the example of a 97.2% recovery ofethanolamine with steam alone should not be taken as specifying the useof excessive amounts of steam such as 60 gm. per min. per kilo ofcharge, but that a substantially complete recovery of ethanolamine maybe obtained with the use of amounts of steam between say 5 to 60 gm. perkilo of charge in well designed commercial vacuum-steam distillationequipment. The amount of steam necessary to effect a substantiallyquantitative recovery of alkylolamine is first, the minimum amountnecessary to effect hydrolysis, plus the amount necessary to preventorsuppress amidization (which may be offset by addition of alkali) plusan amount of team which may be considered as a constant for thedistillation equipment. The latter is dependent upon arrangements in theapparatus which tend toward intimate contact between ample volumes ofsteam and material being decomposed. Such devices are lacking inlaboratory equipment and make the consumption of excessive amounts ofsteam necessary.

The alkylolamine soaps may be considered as pure compounds resultingfrom the interaction of an individual alkylolamine with an individualfatty acid or may comprise mixtures which can be obtained by theinteraction of several alkylolamines with anindividual fatty acid, bytheinteraction of an individual alkylolamine with several fatty acids, orby the interaction of several alkylolamines with several fatty acids.

The alkylolamines may be considered as ammonia substitution compounds inwhich one or more of the hydrogen atoms of the ammonia or partiallysubstituted placed by a corresponding number of hydroxammonia moleculeare reylated alkyl groups which may or may not be further substituted.The term alkylolamine is intended to embrace the primary, secondary andtertiary alkylolamines of which monoethanolamine, methylmonoethanolamine, and dimethyl monoethanolamine may be considered as thefirst members as the corresponding methanol compounds do notexist. Thehomologous propanolamines, butanolamines, pentanolamines may be alsorecovered from their soaps.

' The fatty acid component of the soap may be a saturated carboxylicacid as palmitic acid, stearic acid, etc. or may comprise an unsaturatedcarboxylic acid as oleic acid, elaidic acid, etc. Further, acids ashydnocarpic, chaulmoogric acid, etc. may be regarded as cyclicsubstituted fatty acids and are contemplated when reference is had to afatty acid. Polycarboxylic acid components may comprise the highermalonic homologues such as adipic, pimclic, suberic, azelaic, sebacic.

While we have in the foregoing described in some detail the preferredembodiment of our invention and some variants thereof, it will beunderstood that this is only for the purpose of making the inventionmore clear and that the invention is not to be regarded as limited tothe details of operation described, nor is it dependent upon thesoundness or accuracy of the theories which we have advanced as to thereasons for the advantageous results attained. On the other hand, theinvention is to be regarded as limited only by the terms of theaccompanying claims, in which it is our intention to claim all noveltyinherent therein as broadly as is possible in view of the prior art.

We claim as our invention:

1. The process for the recovery of free alkylolamine from its compoundwith a fatty carboxylic acid which comprises liquefying said compound bythe application of heat and distilling to separate the alkylolamine fromthe fatty carboxylic acid.

2. The process for the recovery of free alkylolamine from its compoundwith a fatty carboxylic acid which comprises subjecting said compound toa steam-distillation whereby the alkylolamine is recovered from thefatty carboxylic acid.

3. The process for the recovery of free alkylolamine from its compoundwith a fatty carboxylic acid which comprises subjecting said compound toa steam distillation under subatmospheric pressure whereby thealkylolamine is recovered.

4. The process for the recovery of free alkylolamine from its compoundwith a fatty carboxylic acid which comprises subjecting said compound toa distillation under subatmospheric pressure with an amount of steam atleast sufficient to prevent the substantial dehydration of the compoundwhereby the alkylolamine is recovered.

5. The process for the recovery of free alkylolamine from its compoundwith a fatty carboxylic acid which comprises subjecting said compound toa distillation under subatmospheric pressure with an amount of steam inexcess of the stoichiometric amount required to hydrolyze all of thecompound present in the distillation unit at any one time whereby thealkylolamine is recovered.

4 acid which comprises subjecting it to a steam distillation at asubatmospheric pressure in the presence of a compound of analkali-forming metal.

7. The process for the recovery of free alkylolamine from analkylolamine extract obtained from oils, fats and waxes of the estertype which comprises subjecting the alkylolamine extract to a steamdistillation at subatmospheric pressure in the presence of a compound ofan alkali-forming metal.

8. The process for the recovery of free alkylolamine from analkylolamine extract obtained from oils, fats and waxes of the estertype which extract contains alkylolamine in the free .and combined statewhich comprises distilling off substantially all of the freealkylolamine and then subjecting the residue to a steam distillation ata subatmospheric pressure whereby the combined alkylolamine is set freeand recovered.

9. The process for the recovery of free monoethanolamine from itscompound with a fatty carboxylic acid which comprises subjecting saidethanolamine compound to steam distillation at subatmospheric pressure.

10. The process'for the recovery of free monoethanolamine from itscompound with a fatty carboxylic acid which comprises subjecting saidethanolarnine compound to a steam distillation at subatmosphericpressure in the presence of a compound of an alkali-forming metal.

11. The process for the recovery of free monoalkylolamine from amonoalkylolamine extract obtained from oils, fats, and waxes of theester type which comprises. subjecting said monoalkylolamine extract toa steam distillation at subatmospheric pressure in the presence of acompoimd of an alkali-forming metal.

12. The process for the recovery of free monoalkylolamine from amonoalkylolamine extract obtained from oils, fats and waxes of the estertype which comprises subjecting said monoalkylolamine extract to a steamdistillation in the presence of a compound of an alkali-forming metal.

13. The process for the recovery of free monoalkylolamine from amonoalkylolamine extract obtained from oils, fats and waxes of the estertype which comprises subjecting said monoalkylolamine extract to a steamdistillation at subatmospheric pressure in the presence of analkali-metal compound.

14. The recovery of free alkylolamine from an alkylolamine compound of afatty carboxylic acid which comprises subjecting said compound to asteam distillation operation in the presence of a compound of analkali-forming metal.

15. The recovery of free alkylolamine from an alkylolamine compound of afatty carboxylic acid which comprises subjecting said compound to asteam distillation operation at subatmospheric pressure in the presenceof a compound of an alkali-forming metal.

16. The recovery of free alkylolamine from an alkylolamine compound of afatty carooxylic acid which comprises subjecting said compound to asteam distillation operation in the presence of a basic alkali metalcompound.

17. The recovery of free alkylolamine from an alkylolamine compound of afatty carboxylic acid which comprises subjecting said compound to asteam distillation operation in the presence of an alkali metal salt ofa carboxylic acid.

18. The recovery of free alkylolamine from an alkylolamine compound of afatty carboxylic acid which comprises subjecting said compound to asteam distillation operation in the presence of an alkali metal salt ofa fatty acid.

LUDWIG ROSENSTEIN. WALTER J. HUND.

